| 摘要 |
PROBLEM TO BE SOLVED: To reduce the irreversible capacity and increase the initial charging/ discharging efficiency by using a carbon material reduced with the reactivity of the active surface functional group to lithium for a negative electrode active material. SOLUTION: A carbon material is chemically processed with alcohol and/or carboxylic acid, the reactivity of the active functional group on the surface portion of the carbon material, particularly the reactivity to lithium, is reduced, and a battery having high initial charging/discharging efficiency and suppressed gas generation and a self-discharge and excellent in characteristics can be obtained. The reason is considered as the fact that the active functional group, e.g. hydroxyl group or carboxyl group, existing on the surface portion of the carbon material is chemically processed with alcohol and/or carboxylic acid into ester, and the reactivity of the functional group, particularly the reactivity to lithium, is reduced. Normally used graphite, acetic acid, and methyl alcohol can be used for the carbon material, carboxylic acid, and alcohol. |
